System for Sensing a Position of a First Member Relative to a Second Member Based on a Radio Frequency Characteristic of a Bias Member

ABSTRACT

A system for sensing a position of a first member relative to a second member based on a radio frequency characteristic of a bias member is disclosed. The bias member may be configured to bias the second member relative to the first member. Radio frequency circuitry may be configured to apply a radio frequency signal to the bias member and provide one or more signals indicative of a position of the first member relative to the second member based on a radio frequency characteristic of the bias member.

PRIORITY CLAIM

The present application claims the benefit of priority of U.S.Provisional Application Ser. No. 62/857,298, filed on Jun. 5, 2019,titled “System for Sensing a Position of a First Member Relative to aSecond Member Based on a Radio Frequency Characteristic of a BiasMember,” which is incorporated herein by reference.

FIELD

The present disclosure relates generally to radio frequency sensors andrelated methods, and more specifically to systems and methods forsensing a. position of a first member relative to a second member basedon a radio frequency characteristic of a bias member.

BACKGROUND

Current position sensor systems for detecting relative position betweentwo members can generally be complex and expensive. For example, someposition sensors require additional mechanical components that cancontact each of the members. Such systems can add undesirable resistanceto relative movement between the members. Other position sensors maygenerally require precisely manufactured components, such as windings.Accordingly, an improved position sensor system would be welcomed in theart.

SUMMARY

Aspects and advantages of embodiments of the present disclosure will beset forth in part in the following description, or may be learned fromthe description, or may be learned through practice of the embodiments.

One example aspect of the present disclosure is directed to a system forsensing a position of a first member relative to a second member basedon a radio frequency characteristic of a bias member. The bias membermay be configured to bias the second member relative to the firstmember. Radio frequency circuitry may be configured to apply a radiofrequency signal to the bias member and provide one or more signalsindicative of a position of the first member relative to the secondmember based on a radio frequency characteristic of the bias member.

Another example aspect of the present disclosure is directed to aposition sensor system for a vehicle pedal. The system may include abase member, a pedal member movable relative to the base member, and abias member configured to bias the pedal member away from the basemember. The system may include radio frequency circuitry configured toapply a radio frequency signal to the bias member and provide one ormore signals indicative of a position of the base member relative to thepedal member based on a radio frequency characteristic of the biasmember.

Another example aspect of the present disclosure is directed to a methodfor sensing a position of a first member relative to a second member.The method may include applying a radio frequency signal to a biasmember that is configured to bias the second member relative to thefirst member; detecting a radio frequency characteristic of the biasmember; and providing one or more signals indicative of a position ofthe first member relative to the second member based on the radiofrequency characteristic of the bias member.

These and other features, aspects and advantages of various embodimentswill become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the present disclosure and, together with thedescription, serve to explain the related principles.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed discussion of embodiments directed to one of ordinary skill inthe art are set forth in the specification, which makes reference to theappended figures, in which:

FIG. 1 depicts a schematic of select portions of an example inductiveposition sensor including radio frequency circuity according to exampleembodiments of the present disclosure;

FIG. 2 depicts a schematic of the example inductive position sensor ofFIG. 1 including an example configuration of a transmit aerial, areceive aerial and a member having a ferrite coating according toexample embodiments of the present disclosure;

FIG. 3 is a schematic drawing of another embodiment of a position sensorsystem employing a leaf spring bias member according to aspects of thepresent disclosure

FIG. 4 depicts a flow diagram of an embodiment of a method for sensing aposition of a first member relative to a second member according toaspects of the present disclosure; and

FIG. 5 is a plot of experimental data collected for a pedal sensorassembly similar to the pedal assembly of FIG. 2.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments, one or moreexamples of which are illustrated in the drawings. Each example isprovided by way of explanation of the embodiments, not limitation of thepresent disclosure. In fact, it will be apparent to those skilled in theart that various modifications and variations can be made to theembodiments without departing from the scope or spirit of the presentdisclosure. For instance, features illustrated or described as part ofone embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that aspects of the presentdisclosure cover such modifications and variations.

Example aspects of the present disclosure are directed to systems andmethods for sensing a position of a first member relative to a secondmember based on a radio frequency characteristic of a bias member (e.g.,a coil spring, or other resilient member). The bias member may beconfigured to bias the second member relative to the first member. Radiofrequency (RF) circuitry may be configured to apply a radio frequencysignal to the bias member and provide one or more signals indicative ofa position of the first member relative to the second member based on aradio frequency characteristic of the bias member.

The radio frequency signal applied to the bias member can be reflectedby the bias member. The reflected radio frequency signal can be detectedby the radio frequency circuitry. The characteristics of the radiofrequency signal(s) (e.g., amplitude, frequency, etc.) that is appliedby the radio frequency circuitry may be selected based on one or morecharacteristics of the system. Example characteristics includedimensions or resonant frequencies of the bias member and/or anysurrounding conductive structure. For instance, the radio frequencysignal may have a frequency that corresponds with a resonant frequencyof the bias member (e.g., a first resonant frequency, second resonantfrequency, etc.).

The radio frequency circuity, or radio frequency circuit, may include aradio frequency generator configured to apply the radio frequency signalto the bias member, The radio frequency circuit may also include aspectrum analyzer that is configured to detect the radio frequencycharacteristic of the bias member. For example, the spectrum analyzermay be configured to detect the reflected radio frequency circuit thatis reflected by the bias member.

In some embodiments, the radio frequency generator and spectrum analyzermay be coupled with the bias member at the same location. For example,the radio frequency generator electrically may be coupled with the biasmember at a first location of the bias member and configured to applythe radio frequency signal to the bias member at the first location. Thespectrum analyzer may be electrically coupled with the bias member atthe first location of the bias member and configured to detect the radiofrequency signal reflected by the bias member at the first location. Forexample, the system may include a splitter connected with the frequencygenerator, spectrum analyzer, and/or the bias member such that each ofthe frequency generator and spectrum analyzer can be coupled with thebias member at the first location.

In other embodiments, however, the spectrum analyzer may be coupled withthe bias member at a second location that is distinct or spaced apartfrom the first location. The second location may be defined at anylocation along the bias member. For instance, in one embodiment, thesecond location may be defined at an end of the bias member that isopposite the first location, In such embodiments, the radio frequencysignal detected by the spectrum analyzer may correspond with aninsertion loss (S_(1,2)) of the bias member.

Example aspects of the present disclosure are directed to a positionsensor system for a vehicle pedal. For example, the system may beconfigured to detect the position of a pedal member, such as anaccelerator pedal, brake pedal etc.

In some embodiments, the bias member may be coupled to each of the firstmember and second member. For example, the bias member may be configuredto bias the second member away from the first member.

In some embodiments, the second member may be pivotally coupled to thefirst member.

In some embodiments, the bias member may be or include a coil spring.

In some embodiments, the radio frequency circuity may include a radiofrequency generator electrically coupled with the bias member at a firstlocation of the bias member and configured to apply the radio frequencysignal to the bias member at the first location.

In some embodiments, the radio frequency circuity may include a spectrumanalyzer electrically coupled with the bias member at the first locationof the bias member location and configured to detect the radio frequencysignal reflected by the bias member at the first location.

In some embodiments, the system may include a splitter having a firstport, a second port, and a third port. The first port may be connectedto the bias member at the first location. The second port may beconnected to the frequency generator. The third port may be connected tothe spectrum analyzer such that each of the frequency generator andspectrum analyzer are electrically coupled with the bias member at thefirst location.

In sonic embodiments, the radio frequency circuity may include aspectrum analyzer that is configured to detect an amplitude of areflected radio frequency signal reflected by the bias member.

In some embodiments, the signal(s) indicative of the position of thefirst member relative to the second member provided by the radiofrequency circuity may be positively correlated with the amplitudedetected by the spectrum analyzer.

In some embodiments, the radio frequency signal may include a fixedamplitude sinusoidal signal. The fixed amplitude sinusoidal signal mayhave a frequency that ranges from about 50 MHz to about 5 GHz, in someembodiments from about 100 MHz to about 4 GHz, in some embodiments fromabout 150 MHz to about 2 GHz, and in some embodiments from about 200 MHzto about 1 GHz.

Another example aspect of the present disclosure is directed to aposition sensor system for a vehicle pedal. The system may include abase member, a pedal member movable relative to the base member, and abias member configured to bias the pedal member away from the basemember. The system may include radio frequency circuitry configured toapply a radio frequency signal to the bias member and provide one ormore signals indicative of a position of the base member relative to thepedal member based on a radio frequency characteristic of the biasmember.

In some embodiments, the pedal member may include an accelerator pedal

In some embodiments, the bias member may be coupled to each of the basemember and pedal member.

In sonic embodiments, the pedal member may be pivotally coupled to thebase member.

In some embodiments, the bias member may include a coil spring.

In some embodiments, the radio frequency circuity may include a radiofrequency generator electrically coupled with the bias member at a firstlocation of the bias member and configured to apply the radio frequencysignal to the bias member at the first location.

In some embodiments, the radio frequency circuity may include a spectrumanalyzer electrically coupled with the bias member at the first locationof the bias member location and configured to detect the radio frequencysignal reflected by the bias member at the first location.

In sonic embodiments, the system may include a. splitter having a firstport, a second port, and a third port. The first port may be connectedto the bias member at the first location. The second port may beconnected to the frequency generator. The third port may be connected tothe spectrum analyzer such that each of the frequency generator andspectrum analyzer are electrically coupled with the bias member at thefirst location.

In some embodiments, the radio frequency circuity may include a spectrumanalyzer configured to detect an amplitude of a reflected radiofrequency signal reflected by the bias member.

In some embodiments, the signal(s) indicative of the position of thebase member relative to the pedal member may be positively correlatedwith the amplitude detected by the spectrum analyzer.

In some embodiments, the radio frequency signal may include a fixedamplitude sinusoidal signal. For example, the fixed amplitude sinusoidalsignal may have a frequency that ranges from about 50 MHz to about 2GHz.

Another example aspect of the present disclosure is directed to a methodfor sensing a position of a first member relative to a second member.The method may include applying a radio frequency signal to a biasmember that is configured to bias the second member relative to thefirst member; detecting a radio frequency characteristic of the biasmember; and providing one or more signals indicative of a position ofthe first member relative to the second member based on the radiofrequency characteristic of the bias member.

FIG. 1 is a schematic drawing of a position sensor system 100 accordingto aspects of the present disclosure. The system 100 may include a firstmember 102 and a second member 104 movable relative to the first member102, for example as illustrated by arrow 106. A bias member 108 may beconfigured to bias the second member 104 relative to the first member102. For example, bias member 108 may be configured to bias the secondmember 104 towards and/or away from the first member 102. The system 100may include radio frequency circuitry, such as a radiofrequency circuit110. The radiofrequency circuit 100 may be configured to apply a radiofrequency signal to the bias member 108 and provide one or more signalsindicative of a position of the first member 102 relative to the secondmember 104 based on a radio frequency characteristic of the bias member108.

The bias member 108, first member 102, and second member 104 may have avariety of configurations. For example, the first member 102 may bedirectly coupled with the second member 104 (e.g., pivotally coupled).As another example, one or more additional members may be coupled withthe first member 102 and/or second member 104 such that the first member102 is articulated with respect to the second member 104. As anotherexample, the first member 102 and/or second member 104 may be movable ona track or may have an articulated configuration such that the firstmember 102 is movable relative to the second member 104. In someembodiments, the first member 102 may be free of direct connection withthe second member. In other embodiments, the first member 102 may becoupled (e.g., pivotally coupled) to the second member 104. The secondmember 104, however, may be movable relative to the first member 102 inany suitable known configuration.

The bias member 108 may have a variety of configurations. For example,the bias member 108 may be a spring having a helical or conicalconfiguration. In other embodiments, however, the bias member 108 may beconfigured as a leaf spring (for examples as described with reference toFIG. 3) or any other suitable resilient member.

The radiofrequency circuit 110 may include a radio frequency generator112 electrically coupled with the bias member 108 at a first location114 of the bias member 108 and configured to apply the radio frequencysignal to the bias member 108 at the first location 114. The radiofrequency generator 112 may be configured to apply the radio frequencysignal to the bias member 108 at the first location 114. The radiofrequency signal may have a variety of suitable attributes, such asfrequency, amplitude, modulation, etc. For example, the radio frequencysignal may include a fixed amplitude sinusoidal signal. The fixedamplitude sinusoidal signal may have a frequency that ranges from about50 MHz to about 2 GHz.

The characteristics of the radio frequency signal (e.g., amplitude,frequency, etc.) applied by the radio frequency generator 112 may beselected based on characteristics of the system 100. Examplecharacteristics include size or resonant frequencies of the bias member108 and/or any surrounding conductive structure.

The radiofrequency circuit 110 may include a spectrum analyzer 116 thatis electrically coupled with the bias member 108 at the first location114 of the bias member 108 and configured to detect the radio frequencysignal reflected by the bias member 108 at the first location 114, forexample as described in greater detail below.

The system 100 may include a splitter 118 having a first port 120, asecond port 122, and a third port 124. The first port 120 of thesplitter 118 may be connected to the bias member 108 at the firstlocation 114 (e.g., by a first cable 126). The second port 122 of thesplitter 118 may be connected to the frequency generator 112 (e.g., by asecond cable 128). The third port 124 may be connected to the spectrumanalyzer 116 (e.g., by a third cable 130) such that each of thefrequency generator 112 and spectrum analyzer 116 are electricallycoupled with the bias member 108 at the first location 114.

The first location 114 may be located at an end of the bias member 108,for example as illustrated in FIG. 1. In other embodiments, however, thefirst location 114 may be located at any suitable location along thebias member 108, for example at a middle location of the bias member108. Alternatively, the radiofrequency circuit 110 may be coupled with aconductive member that is electrically coupled with the bias member 108.For example, the first member 102 and/or second member 104 may beconductive and electrically coupled with the bias member 108. Theradiofrequency circuit 110 may be coupled with the first member 102and/or second member 104 or otherwise located sufficiently near the biasmember 108 to facilitate connection with the bias member 108.

The system 100 may include a conductive ground layer 132 arrangedproximate the bias member 108. As used herein, “proximate” can refer toa distance that is sufficiently small such that the presence of theconductive ground layer 132 affects the radio frequency characteristicof the bias member 108 by a measurable amount. For example, theconductive ground layer 132 may be spaced apart from the bias member 108by a distance that is less than a length 134 of the bias member 108.Alternatively, the conductive ground layer 132 may be spaced apart fromthe bias member 108 by a distance that is less than a width 136 of thebias member 108. The conductive ground layer 132 may be coupled to thefirst member 102, second member 104, or another suitable surroundingstructure near the bias member 108.

The spectrum analyzer 116 may configured to detect and/or analyze theradio frequency characteristic of the bias member 108. For example, thespectrum analyzer 116 may be configured to detect and/or analyze radiofrequency signals received via the third cable 130. Example radiofrequency characteristics include frequency, amplitude, DC bias, orother characteristics of the received radio frequency signals. Forinstance, the radio frequency characteristic may include an amplitude ofa reflected radio frequency signal that is reflected by the bias member108. In this example, the reflected radio frequency signal maycorrespond with a. return loss (S₁₁) of the bias member 108, The signalsindicative of the position of the first member 102 relative to thesecond member 104 may be positively correlated with the amplitudedetected by the spectrum analyzer 116,

In other embodiments, however, the spectrum analyzer 116 may be coupledwith the bias member 108 at a second location that is distinct or spacedapart from the first location 114. The second location may be defined atany location along the bias member 108. For instance, in one embodiment,the second location may be defined at an end 134 of the bias member 108that is opposite the first location 114. In such embodiments, the radiofrequency signal detected by the spectrum analyzer 116 may correspondwith an insertion loss (S₁,7) of the bias member 108.

FIG. 2 is a schematic illustration of a position sensor system 200 for avehicle pedal. For example, the pedal member 202 may be or include anaccelerator pedal for a vehicle. The system 200 may be generallyconfigured as the system 100 described above with respect to FIG. 1. Forexample, the system 200 may include a base member 204 and a pedal member202 movable relative to the base member 204, for example as illustratedby arrow 206. The bias member 208 may be coupled to each of the basemember 204 and the pedal member 202. The pedal member 202 may bepivotally coupled to the base member 204, for example at a pivotlocation 203, Thus, the bias member 208 may be configured to bias thepedal member 202 away from the base member 204, for example towards anuncompressed position.

The system 200 may include radio frequency circuitry, such as a radiofrequency circuit 210, for example as described with reference to theradio frequency circuit 100 of FIG. 1. The radio frequency circuit 210may be configured to apply a radio frequency signal to the bias member208. The radio frequency circuit 210 may be configured provide one ormore signals indicative of the position of the pedal member 202 relativeto the base member 204 based on a radio frequency characteristic of thebias member 208. For example, the radio frequency circuit 200 mayinclude a radio frequency generator 212 electrically coupled with thebias member 208 at a first location 214 of the bias member 208 andconfigured to apply the radio frequency signal to the bias member 208 atthe first location 214. The radio frequency circuit 210 may include aspectrum analyzer 216 electrically coupled with the bias member 208 atthe first location 214 of the bias member 208 and configured to detectthe radio frequency signal reflected by the bias member 208 at the firstlocation 214.

The system 200 may include a splitter 218, for example as describedabove with reference to the splitter 118 of FIG. 1. The splitter 218 maybe connected with the frequency generator 212, spectrum analyzer 216,and/or the bias member 208, for example as described above withreference to the splitter 118 of FIG. 1.

The system 200 may include a conductive ground layer 232, for example asdescribed with reference to the conductive ground layer 132 of FIG. 1.The conductive ground layer 232 may be proximate the bias member 208such that the conductive ground layer 232 affects the radio frequencycharacteristic of the bias member 208. The conductive ground layer 232may be spaced apart from the bias member 208 by a distance that is lessthan a length of the bias member 208. Alternatively, the conductiveground layer 232 may be spaced apart from the bias member 208 by adistance that is less than a width of the bias member 208. Theconductive ground layer 232 may be coupled to the base member 204 orpedal member 202, or another suitable surrounding structure near thebias member 208.

FIG. 3 is a schematic drawing of another embodiment of a position sensorsystem 300 employing a leaf spring bias member 308 according to aspectsof the present disclosure. The position sensor system 300 may generallybe configured as the position sensor system 100 described above withreference to FIG. 1 except that the leaf spring bias member 308 may beemployed. The reference numerals of FIG. 3 may generally correspond withthe reference numerals of FIG. 1. As shown in FIG. 3, movement of thefirst member 302. relative to the second member 304 may cause deflectionof the leaf spring bias member 308. The leaf spring bias member 308 maybe coupled with the first and second members 302, 304 in a cantileverconfiguration. The first member 302 may be coupled at one end of theleaf spring bias member 308. The second member 304 may be coupled at anopposite end of the leaf spring bias member 308. However, it should beunderstood that other suitable configurations may be employed. Forexample, the first or second member 302, 304 may be coupled with theleaf spring bias member 308 at an intermediate position (e.g., at amiddle of the leaf spring bias member 308). In such configurations, oneor more of the ends of the leaf spring bias member 308 may be mounted tosupporting structure.

The radiofrequency circuit 310 may be configured to apply a radiofrequency signal to the leaf spring bias member 308 and provide one ormore signals indicative of a position of the first member 302 relativeto the second member 304 based on a radio frequency characteristic ofthe leaf spring bias member 308, for example as described above withreference to FIGS. 1 and 2. It should be understood that the bias membermay have other configurations.

FIG. 4 illustrates a flow diagram of an embodiment of a method 400 forsensing a position of a first member relative to a second memberaccording to aspects of the present disclosure. Although FIG. 3 depictssteps performed in a particular order for purposes of illustration anddiscussion, the methods discussed herein are not limited to anyparticular order or arrangement. One skilled in the art, using thedisclosures provided herein, will appreciate that various steps of themethods disclosed herein can be omitted, rearranged, combined, and/oradapted in various ways without deviating from the scope of the presentdisclosure. Moreover, the method 400 may be described herein withreference to the sensor assemblies 100, 200, 300 described above withreference to FIGS. 1 through 3. However, it should be appreciated thatthe disclosed method 400 may be used for sensing a position of a firstmember relative to a second member using a bias member having any othersuitable configuration.

The method 400 may include, at (402), applying a radio frequency signalto a bias member that is configured to bias the second member relativeto the first member, for example as described above with reference tothe sensor assemblies 100, 200 of FIGS. 1 and 2.

The method 400 may include, at (404), detecting a radio frequencycharacteristic of the bias member. Example radio frequencycharacteristics include frequency, amplitude, dc bias or othercharacteristics of the received radio frequency signals. For instance,the radio frequency characteristic may include an amplitude of areflected radio frequency signal that is reflected by the bias member108, for example as described above with reference to the sensorassemblies 100, 200 of FIGS. I and 2.

The method 400 may include, at (406), providing one or more signalsindicative of a position of the first member relative to the secondmember based on the radio frequency characteristic of the bias member,for example as described above with reference to the sensor assemblies100, 200, 300 of FIGS. 1 through 3.

EXAMPLE

FIG. 5 illustrates experimental data collected for a pedal sensorassembly that was fabricated similar to the pedal assembly 200 of FIG.2. A radiofrequency signal having a frequency of about 656 MI-Iz wasapplied to the bias member at a first location. The radiofrequencycircuit detected the amplitude of a reflected radiofrequency circuit atthe first location. It was discovered that the reflected radio signal(vertical axis) was approximately linearly positively correlated withthe compression of the bias member (horizontal axis). In an uncompressedposition (0% compression), a sinusoidal signal having a frequency ofabout 656 MHz and an amplitude of about 1.19 mV was detected. In a fullycompressed position (100% compression), a sinusoidal signal having afrequency of about 656 MHz and an amplitude of about 2.18 mV wasdetected.

The radio frequency circuitry can include processing circuitryconfigured to calculate the percent compression of the bias member basedon the detected amplitude of the reflected radio frequency signal. Forinstance, the processing circuitry can employ a lookup table, acorrelating formula (e.g., empirically or theoretically determined),and/or any other suitable means for calculating the percent compressionbased on the amplitude of the reflected radio frequency signal.

While the present subject matter has been described in detail withrespect to specific example embodiments thereof, it will be appreciatedthat those skilled in the art, upon attaining an understanding of theforegoing may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, the scope of the presentdisclosure is by way of example rather than by way of limitation, andthe subject disclosure does not preclude inclusion of suchmodifications, variations and/or additions to the present subject matteras would be readily apparent to one of ordinary skill in the art.

What is claimed is:
 1. A position sensor system comprising: a firstmember: a second member movable relative to the first member; a biasmember configured to bias the second member relative to the firstmember; and radio frequency circuitry configured to apply a radiofrequency signal to the bias member and provide one or more signalsindicative of a position of the first member relative to the secondmember based on a radio frequency characteristic of the bias member. 2.The position sensor system of claim 1, wherein the bias member iscoupled to each of the first member and second member.
 3. The positionsensor system of claim 1, wherein the bias member is configured to biasthe second member away from the first member.
 4. The position sensorsystem of claim 1, wherein the second member is pivotally coupled to thefirst member.
 5. The position sensor system claim 1, wherein the biasmember comprises a coil spring.
 6. The position sensor system of claim1, wherein the radio frequency circuity comprises a radio frequencygenerator electrically coupled with the bias member at a first locationof the bias member and configured to apply the radio frequency signal tothe bias member at the first location.
 7. The position sensor system ofclaim 6, wherein the radio frequency circuity comprises a spectrumanalyzer electrically coupled with the bias member at the first locationof the bias member and configured to detect the radio frequency signalreflected by the bias member at the first location.
 8. The positionsensor system of claim 7, further comprising a splitter having a firstport, a second port, and a third port, and wherein the first port isconnected to the bias member at the first location, and wherein thesecond port is connected to the frequency generator, and wherein thethird port is connected to the spectrum analyzer such that each of thefrequency generator and spectrum analyzer are electrically coupled withthe bias member at the first location.
 9. The position sensor system ofclaim 1, wherein the radio frequency circuity comprises a spectrumanalyzer configured to detect an amplitude of a reflected radiofrequency signal reflected by the bias member.
 10. The position sensorsystem of claim 9, wherein the one or more signals indicative of theposition of the first member relative to the second member provided bythe radio frequency circuity are positively correlated with theamplitude detected by the spectrum analyzer.
 11. The position sensorsystem of claim 1, wherein the radio frequency signal comprises a fixedamplitude sinusoidal signal.
 12. The position sensor system of claim 11,wherein the fixed amplitude sinusoidal signal has a frequency thatranges from about 50 MHz to about 2 GHz.
 13. A position sensor systemfor a vehicle pedal comprising: a base member; a pedal member movablerelative to the base member; a bias member configured to bias the pedalmember away from the base member; radio frequency circuitry configuredto apply a radio frequency signal to the bias member and provide one ormore signals indicative of a position of the base member relative to thepedal member based on a radio frequency characteristic of the biasmember.
 14. The position sensor system of claim 13, wherein the pedalmember comprises an accelerator pedal.
 15. The position sensor system ofclaim 13, wherein the bias member is coupled to each of the base memberand pedal member, wherein the pedal member is pivotally coupled to thebase member.
 16. The position sensor system of claim 13, wherein thebias member comprises a coil spring.
 17. The position sensor system ofclaim 13, wherein the radio frequency circuity comprises a radiofrequency generator electrically coupled with the bias member at a firstlocation of the bias member and configured to apply the radio frequencysignal to the bias member at the first location.
 18. The position sensorsystem of claim 17, wherein the radio frequency circuity comprises aspectrum analyzer electrically coupled with the bias member at the firstlocation of the bias member and configured to detect the radio frequencysignal reflected by the bias member at the first location, wherein theposition sensor system further comprises a splitter having a first port,a second port, and a third port, and wherein the first port is connectedto the bias member at the first location, and wherein the second port isconnected to the frequency generator, and wherein the third port isconnected to the spectrum analyzer such that each of the frequencygenerator and spectrum analyzer are electrically coupled with the biasmember at the first location.
 19. The position sensor system of claim13, wherein the radio frequency circuity: comprises a spectrum analyzerconfigured to detect an amplitude of a reflected radio frequency signalreflected by the bias member, wherein the one or more signals indicativeof the position of the base member relative to the pedal member arepositively correlated with the amplitude detected by the spectrumanalyzer.
 20. A method for sensing a position of a first member relativeto a second member, the method comprising: applying a radio frequencysignal to a bias member that is configured to bias the second memberrelative to the first member; detecting a radio frequency characteristicof the bias member; and providing one or more signals indicative of aposition of the first member relative to the second member based on theradio frequency characteristic of the bias member.